Provincial police say a Norfolk farmer alerted them to a grow op that was planted in his field.

They say, on Monday the farmer discovered that someone cleared a section of his field and planted about 25 marijuana plants.

The farm was located on Windham Road 7, in Norfolk County.

Police say typically, marijuana crops are harvested in late August and up until the beginning of October.

During that time, the illegal growers will head to rural areas to care for and harvest the marijuana plots.

Typically, these illicit crops are located in swamps, corn fields, wooded areas, along rivers and on rural, rental properties with large acreage.

Police say, the most common signs that a grow-op has moved into a local field are abandoned vehicles parked on the side road or trails, bags of fertilizer, planting trays or chemicals located in remote areas, cleared out areas in swamps, wooded areas or corn fields.

Police warn that in some cases, outdoor marijuana grows are guarded or protected by booby-traps.  

If you suspect there might an outdoor grow in a field or swamp area, police say don't touch the plants, instead, leave the area  immediately, record any license plate or GPS information and contact police.